This laboratory has reported on the elucidation of the carbohydrate structures and immunochemistry of pig submaxillary mucins. Presently, we are studying the primary peptide structure of glycopeptides prepared from these mucins by exhaustive pronase treatment. In addition to studies on the chemistry of epithelial mucins, we are investigating the regulation of glycosyltransferase activities and the biogenesis of cellular membranes, specifically zymogen granule membranes. Changes in galactosyltransferase activities in pancreas, liver and gut of the developing rat have been reported. Variations in glycosyltranferase activities occur in parotid glands of isoproterenol-treated rats. These observations are currently being investigated in our laboratory.